Network TV’s most charming serial killer is back. Or is he? Joe Carroll (James Purefoy) may have lost his followers and his freedom at the end of last season’s “The Following” but there’s a new leader in town, ready to take up the job of making FBI agent Ryan Hardy’s (Kevin Bacon) life miserable. It’s crazy evil twin Mark Gray (Sam Underwood), nuttier than before and calling the shots on the ultimate revenge plan. Or is he?